The present invention relates, in general, to control apparatus for motor driven closures which having obstacle detection capabilities, and more particularly, to motor controls with obstacle detection capabilities for moveable closures used in vehicles.
Electric motor drives for windows, sliding roofs and van doors are commonly employed in motor vehicles to automatically move the closure panel or door between open and closed positions. However, an automated closing system can be dangerous if it cannot accurately detect an obstruction in its path of travel.
Government regulations specify that any automatic closure system must be equipped with an anti-pinch safety feature which meets FMVSS118. Because of the safety concerns with these types of obstacle detection systems, sometimes what is intended to be a convenience item on a vehicle becomes an annoyance feature. This is because every obstacle detection design has to strike a balance between being too sensitive or not being sensitive enough. If an obstacle detection design is too sensitive, slight variations in the load on the motor can cause the system to erroneously detect an obstacle and reverse the motor rotation thereby moving the closure panel back to the open position. This is often referred to as a xe2x80x9cfalse reversal.xe2x80x9d False reversals are an annoyance because the automatic closure system did not close when the operator of the vehicle initiated a closed command, thus requiring the operator to reinitiate the closed command. If an obstacle detection design is not sensitive enough, then the force on a pinched object, i.e., an arm or hand, etc., may exceed the government regulated force limit of 100 Newtons.
There are two basic implementation strategies for anti-pinch obstacle detection systems. The first approach uses sensors that monitor the closure path. Sensors in the seal around a vehicle window, or an infrared light curtain are the most common approaches. However, this approach is usually very costly to implement.
The second approach is a motor-based system. This type of system detects obstructions in the closure path by sensing changes in the load on the motor. Most motor-based obstacle detection systems in use today fall into two categories. One type uses a current shunt to measure the current through the motor. The other approach uses a ring magnet on the motor armature together with a Hall effect sensor to produce a digital pulse train that corresponds to the period of rotation the armature. These two methods are respectively referred to as current-sensing and speed-sensing approaches.
However, many of the obstacle detection systems are xe2x80x9chistory basedxe2x80x9d meaning that such systems keep track through memory storage of previous data points, i.e., motor speed, motor current, etc., and compare the current run or motor operation cycle to past data to determine if changes have occurred which could be obstacles. However, such xe2x80x9chistory basedxe2x80x9d systems require considerable processing time and therefore are slower in response to a detected obstacle. Such systems also require a large memory to store the historical data points.
Examples of environmental conditions that may affect or cause variations in motor speed include the applied voltage, the ambient temperature, joints or weld points in the track of the closure assembly, such as the seal and channel that a side door window travels in, accelerations of the assembly in the X, Y or Z axes, etc. For an automotive product, environmental conditions may also include battery voltage when the car engine is off versus alternator voltage when the engine is running. Cold weather, on the other hand, causes the rubber seals around the window to become stiff and create more drag on the glass during movement of the glass and when the glass enters the upper seals at the closed position.
If a vehicle hits a pothole or speed bump, the window glass experiences acceleration in the Z axis. This acceleration of the mass of the window glass causes a reaction force at the motor armature which, in turn, causes a variation in the speed of the motor.
Any one of these conditions can cause a significant deceleration of the motor armature, thus causing a control algorithm to detect an obstacle and reverse the direction of movement of the window glass when no obstacle is actually present in the closure path of the window.
Existing obstacle detection systems state that they can detect the presence of rough road. However, it appears that such detection is at the expense of maintaining a sensitive pinch force level. For example, if a windowlift anti-pinch system has a typical pinch force of 80 Newtons, during rough road the allowable pinch force level is raised to 150-180 Newtons. While this method does limit the possibility of a false reversal, it does not maintain an acceptable limit on the pinch force. Further, these pinch forces may not meet government set levels.
Thus, it would be desirable to provide an obstacle detection system for a moveable closure which addresses the deficiencies in previously devised obstacle detection systems. It would also be desirable to provide an obstacle detection system which has a quicker response time, and smaller memory requirements than previously devised obstacle detection systems. It would also be desirable to provide an obstacle detection system which includes compensation for start-up transients.
The present invention is a power panel apparatus having a unique, robust obstacle detection control to reverse the direction of movement of the panel when an obstacle is detected in the path of movement while preventing false reversals due to environmental induced faults, such as startup transient, rough road, end of zone seal entry, voltage and temperature variations, movement bind positions, and multi-zone time or position-based step functions.
In one aspect, the inventive powered movable panel control apparatus is used with a panel movable between first and second positions, an electric motor having an armature for driving the panel between the first and second positions, means for detecting deceleration of a motor armature. The control includes timer means, responsive to the detecting means, for generating consecutive time periods between a predetermined amount of rotation of the armature.
The present invention also defines a method of controlling a power panel including the steps of:
determining deceleration of the motor armature;
classifying a degree of relative deceleration with respect to a threshold defining a potential obstacle in the path of movement of a panel driven by the motor;
assigning a weighted value to the relative deceleration of the motor armature;
accumulating successive weighted values as a total cumulative weight value;
comparing the total cumulative weighted value with a total cumulative weight defining an obstacle in the path of movement of the panel; and
reversing the direction of movement panel when the total cumulative weighted value equals or exceeds a total cumulative weight defining an obstacle present.
The present power panel apparatus and method provides a robust control for detecting an obstacle in the path of movement of a panel while preventing false reversals due to any one or more of a number of factors including one or more of startup transient, rough road, end of zone seal entry, voltage and temperature variations, and movement bind positions.